Effects of porous tantalum on periprosthetic bone remodeling around metaphyseal filling femoral stem: a multicenter, prospective, randomized controlled study

Goro Motomura,Yasuharu Nakashima,Ryosuke Nakanishi,Hiroshi Imai,Akihiro Sudo,Mitsuhiro Morita,Naohiko Mashima,Harumoto Yamada,Masahiro Hasegawa,Naoto Mitsugi

doi:10.1038/s41598-022-04936-2

Abstract

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA). The use of porous tantalum on the proximal surface of the femoral stem is expected to decrease postoperative bone loss around the prosthesis through early fixation. We conducted a multicenter randomized controlled study to determine if porous tantalum could reduce periprosthetic bone loss after THA. From October 2012 to September 2014, 118 patients (mean age, 61.5 years; 107 females and 11 males) were prospectively enrolled and were randomly allocated at a ratio of 1:1 to either a metaphyseal filling stem with a proximal porous tantalum coating (Trabecular Metal) or a conventional metaphyseal filling stem with fiber mesh coating (VerSys). Patients underwent dual-energy x-ray absorptiometry scans within 1 week after surgery (baseline) and at 6, 12, and 24 months after surgery to assess periprosthetic bone mineral density (BMD) in the 7 Gruen zones. In addition, the Japanese Orthopaedic Association hip score was assessed before surgery and at 6, 12, and 24 months after surgery. In the proximal periprosthetic region (zones 1 and 7), the Trabecular Metal group had significantly smaller reductions in BMD than the VerSys group throughout the study period. In the VerSys group, significant reductions in BMD compared to baseline were seen at each measurement point in all regions, except in zone 6 at 24 months. In the Trabecular Metal group, no significant reductions in BMD relative to baseline were seen in zones 1, 5, or 6 throughout the study period. Both groups demonstrated similar improvement in Japanese Orthopaedic Association hip scores over the study period. This study demonstrated that a proximally coated stem with porous tantalum has superior results over a conventional stem with titanium fiber mesh in terms of periprosthetic bone remodeling.

Highlights

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA)
A total of 118 suitable patients were prospectively enrolled from October 2012 to September 2014. They were randomly allocated at a ratio of 1:1 to either a proximally coated stem with a porous tantalum surface (Trabecular Metal Primary Hip Prosthesis; Zimmer-Biomet, Warsaw, IN) (Fig. 1A) or a conventional stem with a titanium fiber mesh surface (VerSys HA-TCP Fiber Metal Taper Stem; Zimmer-Biomet) (Fig. 1B)
We examined the effects of porous tantalum on the periprosthetic bone remodeling around the femoral stem

Summary

Introduction

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA). In the Trabecular Metal group, no significant reductions in BMD relative to baseline were seen in zones 1, 5, or 6 throughout the study period Both groups demonstrated similar improvement in Japanese Orthopaedic Association hip scores over the study period. This study demonstrated that a proximally coated stem with porous tantalum has superior results over a conventional stem with titanium fiber mesh in terms of periprosthetic bone remodeling. Coated stems cause less periprosthetic bone loss than fully coated stems[6,7], indicating that the extent of the porous coating is a factor that affects adaptive bone remodeling. Various types of porous coatings, such as porous metals and fiber mesh, have different pore geometrics, mechanical properties, and patterns of bone ingrowth[5] These may influence adaptive bone remodeling around the femoral stem. It has some weaknesses such as a high elastic modulus and low shear strength[12]

Methods

Results

Conclusion